When I publish a project with the responsive template, the max size is locked to the actual image size. It would be better when its just getting blown up.

Second thing, is that its only responsive for the width. When I change the window height, smaller than the aspect, the image is getting cropped. It would be great to keep the aspect of the image no matter if the size is changed for width or height.

1) I believe we discussed blowing images up in one of the previous threads Our original view on this is that blurring images is not generally desired when they happen to be smaller than the current viewer container. But... we will consider auto-enlarging the images beyond their max in the next release as one of the zooming options. It has been on our list of enhancements.

2) Please try relative height (and width) in the parent viewer container, e.g height: 100%, and then I believe you can control your parent aspect according to your specific needs and the viewer will follow. You may need to remove responsiveBaseWidth parameter for this to work the way you need.

PS: "Mobile full page" that you can select on Publish is a fully responsive template, considering 2)